I can understand why this is confusing. It's confusing for me as well. But let's try and interpret it from end of the sentence, moving toward the front:
two-present day phenomena
There are two phenomena. Got it.
one rather than the other of two ... phenomena
They're talking about the first one and not the other one of the two phenomena. Got it.
A past phenomena is more similar to one rather than the other ...
A past phenomena is similar to the first of the two phenomena, not the second.
presenting evidence that ...
There is evidence to support the following statement (about the similar phenomena)
The argument proceeds by presenting evidence that ...
Ok, so now we get the entire picture. There is an argument, the argument presents evidence, the evidence supports the similarity of a past phenomena with one (but not the other) of two present-day phenomena.
Sometimes working from the back to the front is useful. Sometimes not.